In a fuel cell system disposed in a vehicle such as a car, a high-pressure gas tank is used as a supply source of a fuel gas. As this type of gas tank, for example, a gas tank having a reinforcing layer formed on the outer surface of a resin liner (an inner container) is used (see Patent Document 1). The reinforcing layer is usually formed by winding a resin-containing fiber around the outer surface of the resin liner by a filament winding (FW) process, followed by thermal curing.
The above gas tank is requested to have high gas barrier properties to prevent leakage of the fuel gas due to permeation. As a method for ensuring the gas barrier properties, Patent Document 2 discloses a method in which the inner surface of an inner shell of a gas container is covered with a film of a fluorine resin, to prevent the permeation of a natural gas as the fuel gas.